Corals under threat from acidifying seas can only be saved by deep cuts in carbon dioxide emissions, scientists have said, and engineering the chemistry of sea water around coral reefs was only possible on a very small scale. Reuters explains: “In a US-led study, scientists mixed chemicals into a lagoon, cut off from the sea at low tide, at Australia’s One Tree Island to locally reverse the global trend of acidification that makes it harder for corals to build their stony skeletons. They showed that the coral, part of Australia’s Great Barrier reef, grew better when bathed in seawater mimicking conditions before the Industrial Revolution, which ushered in widespread burning of fossil fuels that release carbon dioxide.” Nature explains further: “Scientists have provided the first experimental evidence that rising carbon dioxide emissions are harming coral reefs in the wild…[During the experiment], the rate at which coral reefs in the atoll grew increased by nearly 7% — suggesting that present-day CO2 emissions have slowed down coral growth by making seawater more acidic.” The Guardian, USA Today and MailOnline also report the paper. Two of the paper’s authors have also written an article for the Conversation.

The 13 protesters who were found guilty last month of aggravated trespass were spared jailed yesterday when a magistrate sentenced them to six weeks in prison, but suspended for 12 months. They were ordered to do community service and ordered not to go within 500m of any Heathrow terminal building or within 5m of the perimeter fence, which they cut through as part of their protest last July. They were also fined up to £1,000 each. The Independent reports that the judge “paid tribute to their integrity and conviction, saying there is no doubt they are all committed to tackling global warming and very genuinely believe they are acting in the best interest of society”. The judge added: “I can’t fail to be impressed by the quality of references received for all defendants.” The Guardian and BBC also carry the news. The Guardian has also published portraits of the protesters and carries a comment piece by Danni Pafford, one of the “Heathrow 13”.

The window of opportunity for humanity to cap global warming by slashing greenhouse gases is closing faster than previously thought, according to a study published in Nature Climate Change. Earlier estimates of our “carbon budget” have ranged from 590bn to 2.4tn tonnes. The new research says the upper limit is actually half that, some 1.24tn tonnes of CO2. “We have figured out that this budget is at the low end of what studies indicated before,” said lead author Joeri Rogelj, a climate scientist at the International Institute for Applied Systems Analysis in Austria. “If we don’t start reducing our emissions immediately, we will blow it in a few decades…In our proposed carbon budget range, we take into account warming by all human emissions, and thus shave of the top-end of studies that looked at CO2 only.” Climate Home and Climate Central also carry the story.

The head of Scottish Power has underlined the company’s enthusiasm for the renewable energy business in the UK where it intends to invest £6.3bn over the next five years. As Scottish Power gave the green light to plans to build a £2.5bn windfarm off East Anglia yesterday, chief corporate officer Keith Anderson emphasised the appeal of such assets compared with traditional plants. “Coal and gas generation is not making any money,” complained Mr Anderson, who said the supply of gas and electricity to consumers is a fiercely competitive business. Scottish Power will close the coal fired Longannet power station in Fife next month. However, Mr Anderson said the government needed to do more to encourage firms to build new gas plants as growing numbers of coal-fired generators are closed.

A group of prominent scientists has published a commentary faulting colleagues who have published papers downplaying or dismissing the significance of a 13-year slowdown in warming rates at the planet’s surface. “We shouldn’t sweep the early 2000s warming slowdown under the rug,” said Penn State meteorology professor Michael Mann, one of 11 authors of the commentary published in Nature Climate Change. “The temporary slowdown in no way implies that human-caused warming has ceased or slowed down,” Mann added. “It was temporarily masked by natural factors.” Climate Central explains that several recent papers have called into question whether the surface warming slowdown was significant. “Some of the disagreements boil down to semantics; others relate to interpretations of data.” John Fyfe, the lead author, said he had “no doubt” that the commentary would be misused by climate sceptics, but that he had no hesitations about publishing it. “I don’t think we should be in the business of pandering to the climate deniers.” The paper agreed that framing the slowdown as a “pause” or “hiatus” was “unfortunate” and that “reduced rate of warming” or “temporary slowdown” would be a better way to describe it. Nature News and theWashington Post also cover the paper.

China’s lead climate envoy has hinted the country could exceed planned greenhouse gas cuts for 2020 by up to 10%, as the economy slows and coal use falls. Addressing a conference in Hong Kong, Xie Zhenhua said the country would likely “far surpass” a goal to slash the carbon emissions in a unit of GDP 40-45% on 2005 levels by 2020. The veteran diplomat, who negotiated for China at last December’s Paris summit, revealed the country could cut its carbon intensity by 50% by the end of the decade.

The U.S. oil and natural gas industry emits more methane than previously thought, says U.S. Environmental Protection Agency Administrator Gina McCarthy. “Methane emissions from existing sources in the oil and gas sector are substantially higher than we previously understood,” McCarthy told IHS CERAWeek, the annual gathering of global oil executives, though she did not quantify the difference.

Big Oil must thwart the movement to leave fossil fuels in the ground, says the world’s most powerful oilman. Addressing executives in Texas, Saudi oil minister Ali Al-Naimi said the industry had to shed its “Dark Side” image and show it was a “force for good”. “As an industry, we should be celebrating that fact, and better explaining the vital importance of these precious natural resources,” he said in a transcript an event in Houston. “We should not be apologising. And we must ignore the misguided campaign to ‘keep it in the ground’ and hope it will go away.”

The US has won a ruling against India at the World Trade Organization after challenging the rules on the origin of solar cells and solar modules used in India’s national solar power programme. In a statement, the US Trade Representative’s office called the ruling a significant victory that would hasten the spread of solar energy across the world and support clean-energy jobs in the US. The US complained to the WTO in 2013 about the Indian solar program, which sought to ease chronic energy shortages in Asia’s third-largest economy without creating pollution. But a requirement that certain cells and modules be made in India fell afoul of WTO rules on discriminating against imports.

The first export of liquefied natural gas (LNG) from the contiguous United States was due to depart from Louisiana yesterday, the company making the shipment said. Cheniere Energy Partners announced that the LNG is headed for Brazil. “This historic event opens a new chapter for the country in energy trade,” Neal Shear, head of Cheniere, said in a statement. Some environmentalists have objected, citing the harms from hydraulic fracturing and the climate impacts of natural gas.

Nicholas Stern calls on scientists, engineers and economists to help policymakers by better modelling the immense risks to future generations, and the potential for action: “Current economic models tend to underestimate seriously both the potential impacts of dangerous climate change and the wider benefits of a transition to low-carbon growth. There is an urgent need for a new generation of models that give a more accurate picture…The next IPCC report needs to be based on a much more robust body of economics literature, which we must create now. It could make a crucial difference…Most current models of climate-change impacts make two flawed assumptions: that people will be much wealthier in the future and that lives in the future are less important than lives now.”

Scientists are often accused of poorly communicating their findings, but improving scientific literacy is everyone’s responsibility, argues the editorial: “It may be wise to provide communications training for scientists, which is an idea that the IPCC is already exploring. But perhaps journalists and politicians should also be sent to science classes — teaching the skills to read science at its source should be a greater priority across the board. Everyone must take their share of responsibility in the march towards more accessible science.”

Nuccitelli says that “predicting how quickly sea levels will rise is a challenge”, but that two new papers have found that the Antarctic ice sheet could melt more quickly than previously thought: “What humans are in the process of doing to the climate makes the transition out of the last ice age look like a casual stroll through the park. We’re already warming the Earth about 20 times faster than during the ice age transition, and over the next century that rate could increase to 50 times faster or more.”

A new study describes why conventional carbon budgets – that account for carbon dioxide warming only – don’t give a real world view of how constrained emissions need to be to meet a given target. For a more than 66% chance of staying below the internationally agreed limit of 2C, the budget allowing for additional warming from all other greenhouse gases is between 590-1,240 billion tonnes of carbon dioxide from 2015 onwards. Yet, current global emissions are around 40 billion tonnes per year, the authors note, highlighting the urgency with which emissions need to come down.

Scientists have found an elegant way to test how much ocean acidification is slowing coral growth in the Great Barrier Reef. The growth rate of coral skeletons increased by 7% after scientists artificially restored the chemistry of the surrounding seawater to preindustrial levels. The use of a passive tracer showed the result was due to the addition of calcium carbonate, which corals use to build their skeletons, rather than any other environmental factor.

A new paper by a group of high profile scientists examines the idea that the rate of surface warming was slower over the 2001–2014 period relative to the 1970s-1990s, despite greenhouse gases continuing to rise. The authors conclude the change of pace was real, rather than an artefact of observational errors, and explain how natural variability alongside changes in aerosol, solar and volcanic activity can be large enough to temporarily speed up or dampen the pace of warming for a decade or more.